Sorry if this has been asked /answered elsewhere on the forum but having mainly paddled plastic (poly) sit-on-top kayaks for the last few years I don't know all that much about the relative merits of fibreglass kayaks. I've surfed all my life and have plenty of fibreglass surfboards, but as kayaks are a different kettle of fish I don't know much about the construction process etc.

I'm aware that poly yaks are a hell of a lot tougher and will cope with abuse (on and off water) a hell of a lot better than a fibreglass yak, but I'd like to get everyones perspective on what are the main benefits of both.

Depends on what you want to do in your seakayak. If it's from A to B you want to go as quickly as possible then a composite boat is probably the go -- something like a Mirage 580 (add a sail and you'll go faster when conditions allow). Coffee cruising in enclosed waters and I'd still go composite. My view is that if you want to get fully immersed in real seakayaking start off with a plastic boat and graduate to a composite boat when you think your skills are up to it (it's interesting to note that many of the experienced paddlers in the NSW Seakayak Club have both composite and plastic boats -- bought in that order). You'll soon learn that a sit-in will provide you with the opportunity to develop a much broader skill set to that on offer from a SOT. As you have identified, the plastic boat is more robust and therefore will better withstand the impact of hitting any rocks you might hit when developing your skills while playing in rock gardens, delving in to sea caves, etc. I started off with a fibreglass boat but with the benefit of hindsight should have chosen plastic.

The downsides of plastic are weight, slower speed and less options on offer for repair to major impact damage (a rare event). Lower capital outlay and robustness are among the benefits.

Composite boats are lighter, faster and offer much more options in respect of repairs to major impact damage. They generally cost a fair bit more than a plastic boat.

If you can launch and retrieve on nice sandy beaches then a composite is fine, I disagree with the speed comparison this depends on which boats you want to compare apple with apple orange with orange. Weight is a factor but needs to considered with each boat.

Skill set is a bit of self determination. Are you going out to enjoy your paddle in moderate conditions or are you going out to push the envelope. The skill improving argument which many claim they achieve by owning composite/rudderless boats issue has intrigued me since I have joined this forum somehow people think that by buying arguably the best sea kayak in the world it improves their skills. I say buy a dog of a boat and paddle it and that will improve your skills. But I'm obviously in the minority here.

I generally paddle in an area which has a lot of oyster encrusted rocks a nice composite boat is going to get very beat up in short amount of time. I own a very good plastic boat with a rudder ( I just thought i"d throw that in to fan the fires).

There is no one simple answer. And every question you may ask will bring forth many conflicting answers.

Look at your local conditions your local shop if you are lucky enough to have one and weigh up the possibilities. If you buy a boat which fails to meet all your objectives over time and your goals will change then you may be able to sell it and buy another.

For me the advantage of a composite boat is just in the weight. Most places I launch from I just have my kayak on my shoulder and a paddle in my hand. Plastic is way harder for me to lug and I would use wheels. As I paddle un laden mostly the bit of extra weight of plastic would probably be better. The only place I have had a really good paddle of a plastic sea kayak was in N Z where I spent a week with a Penguin kayak. Seal launches were heaps of fun and getting in around and onto the rocks was no problem. There is no way I will do that with what I have now. People do though and glass is easier to fix if you do hole it.

OK, so I get the vibe that plastic boats can deo everything a glass/composite boat will do but the composite boats are just 'nicer' to paddle (and perhaps have a bit more 'cool' factor) ?

I'd still be interested to know if theres any REAL difference in top end or cruising speed between a plastic and a glass boat with similar hull shapes/waterline lengths? I've always been of the impression that its the hydrodynamics of the boat that affect the speed, not the material the boat is made from. ??

I also understand that plastic may be a tad heavier than composite boats off the water, but does that really make any difference once you're paddling them? Again, if you have 2 boats (1 plastic, 1 composite) with similar hull shapes and displacement then (in theory) they should both have similar water speed / glide ability should they not?

Also, (sorry for all the questions), what's a 'typical weight of say a Mirage 530/580 against something like a Perception EcoBehzig or similar style of popular poly sea kayak?

I've got a Mirage 580 and an Aquanaut HV. The Mirage is Kevler / Glass and weighs around 24-25kg. The Aquanaut is plastic and weighs +27kg. Speedwise the Aquanaut is marginally slower but its only noticable when in "training mode". In fact I've been on a few paddles with other folk where my Aquanaut is "faster" other glass boats. So, maybe, its got more to do with technique and paddle choice in this instance.

I bought the Aquanaut because I wanted to enjoy the benefits of a rudderless boat (maintaining paddle stroke / edging skills and the way it responds to waves etc). I keep the Mirage for touring (storage space, sail, lazy paddling).

The choice of plastic over composite in the Aquanaut was mostly based on cost. If I didn't have the Mirage I would have purchased the glass Aquanaut. Its nice to have a glass boat.

There is sometimes a bit of creative accounting with these figures by some makers but in general they're close to the mark.

Going down the carbon/kevlar road has more significant weight savings but there has been a body of discussion on this forum about strength vs weight vs material and the perceived advantages/disadvantages of different construction methods. which I won't go into not to mention greater costs.

Dave, the main reason that some people view plastic as inferior is that so many low performance kayaks are made from plastic.Some people refer to some kayaks made from plastic as "Tupperwear". If somebody is just happy to have a craft that floats him/her and uses it without great aspirations most low performance plastic kayaks are great.Since majority of plastic kayaks are not suitable for demanding waters people tend to associate plastic with entry level kayaks.Not so. There are some brilliant plastic kayaks out there. The locally available Valley RM range is phenomenal.And not all plastic kayaks are created equal.The biggets problem that plastic sea kayaks have is non welded waterproof bulkheads.A foam bulkhead will only be waterproof for so long if the kayak is used seriously.Some plastic kayaks have solid plastic bulkheads though.In regards of speed a brand new plastic kayak will have very negligible difference in speed to the same hull shape composite kayak.Please note the wording "new".While most people regard a plastic kayak as indestructibe they tend to abuse it.Dragging a plastic hull over rocks and asphalt (no kidding; I saw somebody schlepping his plastic fantastic along the bitumen from his car to the put in point) will cause the finish to scratch.But it won't ham it, will it? I hear saying.A hull that is scratched a lot will create noticeable drag in the water.So, plastic is great but you still should take care of it.If speed is not your thing and playboating on rocky shores is your scenario, a plastic boat might have advantages over the sexy shiny gel coat.

gnarlydog wrote: Some people refer to some kayaks made from plastic as "Tupperwear".

Yep, I've heard that plenty of times, but I'm also aware that Tupperware is one of the most brilliant inventions of the 20th century (along with bundaberg rum and top deck chocolate )

gnarlydog wrote: Dragging a plastic hull over rocks and asphalt (no kidding; I saw somebody schlepping his plastic fantastic along the bitumen from his car to the put in point) will cause the finish to scratch.So, plastic is great but you still should take care of it.

Yep that would be me. My current yak is 3 years old and has been dragged across roads, rocks, gravel, launched off rock platforms through surf, dropped off the roof of my car, smashed in shorebreaks and even pounded against rocks for 8 hours straight when it broke away from our mothership at night in the Whitsundays last year. At 4.5metres and 28kgs my yak is pretty heavy but it's also put up with plenty of abuse (and yes my top end paddling speed has probably suffered due to that)

I guess that's the reason I'm asking these questions, to gather some info about what sort of sea kayak I should be leaning towards. I'm in no way ANTI glass/composite and I think that glass/comp boats LOOK terrific and obviously paddle fantastically well, but with the levels of abuse I'm likely to dish out I'm worried that a composite boat, in my hands, may not fare all that well.

At this stage I'll be borrowing my brother in laws glass sea kayak for a couple of weeks and having a few paddles so once I've sat and paddled that, I guess I'll have a bit more of an idea about the appeal of both.

Thanks again for all your replies, and if theres any other thoughts on the advantages/disadvantages of poly over composite or vice versa then please feel free to add your 2 cents..

This is a bit of a backward compliment to the boats but it is easier for the amateur to fix a glass boat. The obvious answer to this is "But they need fixing more often" which is probably true. I do like the knowledge that for most eventualities a small tin of resin and glass will fix my kayak. I was snob when I looked at kayaks. I was seriously considering building my own in carbon so for me buying kevlar/glass was a way that suited my own sensibilities. I would be happy paddling the Whitsundays or anywhere nice in a plastic boat too.

Glass is stiffer so the kayak won't change on you as quickly as a plastic boat. Some plastic boats (usually sit ins) seem to get a saggy bottom from what I see. (These are the whitewater boats I have used - not sea kayaks - I have never paddled a plastic sea kayak) Maybe these are the cheap ones. Even so all plastics (fiberglass included) will get softer and more spongy as they get older.

Go down Pete L's path and get both, they both have advantages and disadvantages.

Interestingly, most people who start in a plastic end up in glass. I had both for a while, Raider X and Tasman Express. I just found myself using the Tasman less and less, to the point where I never used it for over 1 year....so I sold it.

from what I can see composite is easier to customise. You can glue things onto poly boats, but unless you prepare the surface with some really aggressive chemicals the bond won't be strong. There are some new structural quality glues that this doesn't apply to but they are quite expensive and not widely available. I don't remember seeing it in any colour but off-white either. They do work though, I can vouch for that personally. Don't get me wrong, I'm actually in the plastic camp, for the next few years anyway, but if you want a boat that you can adapt to your specific needs then composite has a real edge. If you're happy with an off the shelf product then plastic may suit you just as well.

Anyone out there tried putting a mast step into the deck of a poly boat ? That might be my next project